LibreSSL is not yet fully API compatible with OpenSSL 1.0.2 and later,
However many APIs from OpenSSL 1.0.2 and 1.1 are already implemented in
LibreSSL 2.7.0 and later. Old approach works in newer LibreSSL version
as well, but it's not nice to force deprecated functions on LibreSSL
users.

Add additional conditionals for new LibreSSL versions to use the
available new APIs.